A gyratory crusher may be utilized for efficient crushing of material, such as stone, ore, etc. into smaller sizes. An example of a gyratory crusher can be found in U.S. Pat. No. 1,791,584. In such a crusher, a crushing chamber is formed between an outer crushing shell, which is mounted in a frame, and an inner crushing shell, which is mounted on a gyrating crushing head. Material is crushed between the outer crushing shell and the inner crushing shell and crushed material falls by gravity from the crushing chamber to a discharge zone situated below the crushing chamber. Interior of the discharge zone, below the crushing head, is a working part zone holding among other things axial and radial bearings required for the gyrating motion of the crushing head. It is important that dust or other particles do not enter the working part zone to avoid damage to the bearings and contamination of lubricant contained in the working part zone.
U.S. Pat. No. 1,791,584 discloses so called wiping members shaped and arranged to prevent the access of dust to the working part zone. Two upper wiping members, i.e. two circumferential and concentric flanges, are formed in the lower part of the crushing head, interior of the discharge zone and exterior of the working part zone. Each of the upper wiping members cooperates with a lower wiping member integrated in the lower frame of the gyratory crusher. Thus, the upper wiping members gyrate along with the gyrating motion of the crushing head and the lower wiping members are immovable.
To further prevent the admission of fine particles into the working part zone compressed air is supplied into the space defined between the wiping members to create an overpressure. A spring is used to thrust the inner one of the lower wiping members upwardly to minimize passage of pressurized air from the space between the wiping members to the working part zone. Further, the outer one of the lower wiping members is arranged with a clearance to its cooperating upper wiping member to allow passage of pressurized air from the space between the wiping members to the discharge zone.
An object of the invention to provide a gyratory crusher with improved functions for preventing the access of dust and particles to the working part zone of a gyratory crusher.
Another object of the invention is to provide a method of shielding the working part zone of a gyratory crusher from dust and particles.